Optical element package, semiconductor light-emitting device, and lighting device

ABSTRACT

To provide a semiconductor light-emitting device which enhances heat dissipation properties, prevents occurrence of solder crack, and is mounted with the improved accuracy, an optical element package  1  includes a base  10  having a mount portion  13  and through-holes  11  and  12  opposite to each other with the mount portion  13  therebetween, leads  21  and  22  led through the through-holes  11  and  12 , and insulating materials  31  and  32  filled in the through-holes  11  and  12 , wherein the leads  21  and  22  are fixed in a state of being insulated from the base  10  by the insulating materials  31  and  32.

TECHNICAL FIELD

The present invention relates to an optical element package including a base on which an optical element such as an LED is mounted and a lead for electrically connecting the optical element to an external member.

BACKGROUND ART

As an optical element package for packaging therein an optical element such as a light-emitting diode (LED), the following is known: an optical element package including a base with the optical element mounted thereon and a lead for electrically connecting the optical element to an external circuit. An optical element is provided in this optical element package, and the optical element is connected to a conductive member by wire bonding. Then, a seal is formed with a transparent resin. Thus, a semiconductor light-emitting device is fabricated.

FIG. 8 shows a semiconductor light-emitting device disclosed by Patent Literature 1. This semiconductor light-emitting device includes, as a base, a first ceramic substrate 101 and a second ceramic substrate 102 of which a central portion forms a cavity. The upper surface of the first ceramic substrate 101 has a portion on which an LED element 105 is to be mounted. On the inner surface of the second ceramic substrate 102 facing the cavity, a metallic reflector 106 is provided to surround the LED element 105.

On the surface of the first ceramic substrate 101, a conductive pattern 103 for electrically connecting the LED element 105 and an external circuit is formed. The conductive pattern 103 and the LED element 105 are connected by a wire 104. The cavity is filled with a sealing resin 108 such as a silicon resin and thus sealed.

Such a semiconductor light-emitting device is mounted on a mount substrate having an external circuit, and is used for a lighting fixture or the like.

CITATION LIST Patent Literature 1

Japanese Patent Application Publication No. 2003-197947

SUMMARY OF INVENTION Technical Problem

Such a semiconductor light-emitting device has problems in its heat dissipation properties, occurrence of solder crack, and the accuracy in assembling.

For example, in the semiconductor light-emitting device, heat is dissipated from the LED element 105 to the outside via the ceramic substrates 101 and 102 or the sealing resin 108. Accordingly, although the metallic reflector 106 has high thermal conductivity, heat is unlikely to be dissipated to the outside due to the intervening ceramic substrates 101 and 102 or sealing resin 108.

Also, when heat is dissipated from the bottom surface of the package to the mount substrate, the following occurs. Since an external electrode is formed on the surface of the first ceramic substrate 101, thereby protruding beyond the bottom surface 107 of the first ceramic substrate 101, a clearance is formed between the mount substrate and the bottom surface of the package directly below the LED element 105. This clearance causes the low heat dissipation efficiency.

When the semiconductor light-emitting device is to be mounted on a mount substrate made of metals such as copper and aluminum, the conductive pattern 103 and the mount substrate are joined to each other by soldering. Accordingly, when heat cycle test is performed after the device is mounted, the solder joint part becomes stressed due to the thermal expansion difference between the first ceramic substrate 101 and the mount substrate. Here, as described above, since the first ceramic substrate 101 and the conductive pattern 103 are integral with each other, the solder joint part is likely to be cracked.

Plus, as to the problem in the assembling accuracy, since the ceramic substrates 101 and 102 are manufactured by sintering ceramics, it is difficult to form the ceramic substrates 101 and 102 accurately in size. Therefore, when the metallic reflector 106 is joined to each of the ceramic substrates 101 and 102, such joint is fragile. Thus, the metallic reflector is likely to come off by shock.

Also, if the clearance between the ceramic substrate 102 and the metallic reflector 106 is reduced, the metallic reflector 106 joined thereto is likely to be deformed. On the other hand, if the clearance is increased, a void easily occurs in the joint surface between the ceramic substrate 102 and the metallic reflector 106, which results in lowering of the heat dissipation properties.

It is an objet of the present invention to improve the heat dissipation properties, to prevent the occurrence of solder crack and to enhance the accuracy in assembly in connection with the semiconductor light-emitting device.

Solution to Problem

To achieve the above object, the present invention provides an optical element package for packaging an optical element therein including a base having a mount portion on an upper surface thereof for mounting the optical element thereon and a through-hole, a lead passing through the through-hole and to be connected to the optical element, and an insulating material filled in the through-hole and fixing the lead such that the lead is insulated from the base, wherein the lead extends outwardly from the through-hole at one end, and a portion of the lead passing out of the through-hole at the one end is bent in a direction toward an outer circumference of the base so as to extend along the bottom surface of the base.

The optical element package in accordance with the present inventions is more favorable with the following limitations.

The base is made of a material containing a metal, and in particular, made of oxygen-free copper or a copper alloy.

The bottom surface of the base has a protruding portion, and a bottom level of the protruding portion is flush with a bottom level of an extending portion of the lead that extends along the bottom surface of the base.

A portion of the lead that passes through the through-hole has been offset from a center of the through-hole in the direction toward the outer circumference of the base, and the lead is bent toward the center of the base at another end in a vicinity of the mount portion.

A central portion of the upper surface of the base is recessed so that an outer circumferential portion of the base is higher than the mount portion.

A surface of the central portion of the base that is recessed is coated with silver or a silver alloy.

The insulating material is made of highly reflective white glass.

The one end of the lead extends beyond the outer circumference of the base, and is bent upwardly at an endmost portion thereof.

A width of the endmost portion of the lead is smaller than a width of an extending portion of the lead that extends along the bottom surface of the base.

The insulating material intervenes between the bottom surface of the base and an extending portion of the lead that extends along the bottom surface.

The insulating material is made of soda-lime glass or borosilicate glass.

The lead is made of an iron-nickel alloy.

According to the optical element package of the present invention, the mount portion may be integrally formed on the base. However, the optical element package may have an auxiliary base portion fixed in a state of being insulated from the base, and an upper surface of the auxiliary base portion may have a mount portion for mounting the optical element thereon.

In this case, a plurality of auxiliary base portions may be provided for a main body of the base, and an upper surface of each auxiliary base portion may have the mount portion.

An optical element may be provided in an electronic package, and connected to the lead by wire bonding. Thus, a semiconductor light-emitting device can be structured.

The semiconductor light-emitting device may be mounted on a substrate having a wire connected to a driving circuit. Thus, a lighting fixture can be structured.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the optical element package in accordance with the present invention, since the lead is fixed in a state of being electrically insulated from the base by the insulating material, if the base is made of a conductive material, the base and the lead can be kept insulated. Accordingly, when the base is made of a metal material that has good thermal conductivity, heat generated by the optical element is favorably transmitted externally via the base. Thus, the heat can be favorably dissipated.

In particular, the lead extending outwardly from the through-hole is bent relative to a portion of the lead passing through the through-hole in a direction toward the outer circumference of the base so as to extend along the bottom surface of the base. Hence, when the optical semiconductor device is included in the optical element package in accordance with the present invention and the package is assembled on the substrate, since the extending portion of the lead extending along the bottom surface is connected to the mount substrate, the bottom surface of the base immediately below the optical element mount portion is in proximity to or in contact with the mount substrate. Accordingly, the heat generated by the optical element can be transmitted from the mount portion to the immediately underneath portion, thereby being effectively dissipated to the mount substrate.

Also, the lead is not directly connected to the surface of the base, but is fixed thereto via an insulating material. Furthermore, the portion of the lead passing out of the through-hole is bent in the direction toward the outer circumference of the base so that the lead extends along the bottom surface of the base. Thus, the lead can be flexibly deformed to some extent.

Accordingly, even if external force due to the thermal expansion difference between the base and the mount substrate in the package is exerted on the lead, since the force is absorbed by the deformation of the lead, stress applied on the solder joint part is small. Hence, in the heat cycle test after the device is mounted on the substrate, the solder joint part between the lead and the wire of the mount substrate is unlikely to be cracked.

Particularly, when the mount substrate is made of a metal such as copper and aluminum, if the base is made of a metal material, the thermal expansion difference therebetween is reduced. This is very effective in suppressing the occurrence of solder crack.

Also, the optical element package in accordance with the present invention can be manufactured as follows. The base and the lead are separately manufactured. The lead is led through the through-hole of the base, and the through-hole is filled with an insulating material. Thus, with the use of press working, the base and the lead can be manufactured with accuracy.

According to the optical element package in accordance with the present invention, the base made of a material including a metal, such as oxygen-free copper or a copper alloy in particular, is well-conductive. Thus, such an optical element package can have excellent heat dissipation properties.

The base has a protruding portion formed on the back side of the mount portion. The bottom level of the protruding portion and the bottom level of the extending portion of the lead which extends along the bottom surface of the base are flush with each other. With this structure, when the package is mounted on the mount substrate, the bottom level of the protruding portion is in contact with the mount substrate. Thus, the base can more favorably dissipate heat to the mount substrate.

A portion of the lead passing through the through-hole is offset from the center of the through-hole toward the outer circumference of the base. With this structure, if an end portion of the lead in the vicinity of the mount portion is bent toward the center of the base, an area to assure the insulation between the lead and the base can be kept. In other words, if the end portion of the lead is bent toward the center of the base, a pad area is increased. This makes it easier to join the optical element and the lead end portion by wire bonding.

Also, with this structure in which the portion of the lead passing through the through-hole is offset outwardly, when the protruding portion is formed on the bottom surface of the base, a distance between the protruding portion and the lead is longer. This is effective in preventing the lead and the protruding portion from shorting out when the package is mounted on the mount substrate.

The recessed portion is formed in the central portion of the upper surface of the base so that an outer circumferential portion of the base is higher than the optical element mount portion. As a result, the inner surface of the recessed portion can function as a reflector.

Here, when the inner surface of the recessed portion of the base is coated with an alloy containing silver or gold, the reflector can better reflect blue light (short-wavelength visible light).

The insulating material is made of high reflective white glass. This is also effective in enhancement of the reflectivity of the reflector.

When the extending portion of the lead further extends beyond the outer circumference of the base and the endmost portion of the lead is bent upwardly, a fillet is formed on the solder joint part, thereby enhancing the strength of the soldering joint. This can further suppress the occurrence of solder crack.

When the width of the endmost portion of the lead being bent is smaller than the width of the extending portion of the lead extending along the bottom surface of the base, an angular portion is formed in the end portion of the extending portion of the lead. Thus, when the package is assembled, this angular portion can be easily fixed by a jig. This contributes to the improvement in the accuracy in assembling of the package.

When the insulating material also intervenes between the extending portion of the lead and the bottom surface of the base, they can be securely insulated from each other.

When the insulating material is made of soda-lime glass or borosilicate glass, since a glass material is highly viscous compared with a resin, it is generally effective in joining members even if there is a wide clearance therebetween. Thus, the lead can be stably fixed.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are respectively a top view and a bottom view of an optical element package in accordance with an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along the line X-X of FIG. 1;

FIGS. 3A and 3B respectively show a semiconductor light-emitting device having the optical element package with an optical element provided therein, and a state where the semiconductor light-emitting device is mounted on a mount substrate;

FIG. 4 is a process flow chart showing a manufacturing method of the optical element package and the semiconductor light-emitting device;

FIG. 5 shows a metal plate of the lead which is not yet processed to be bent;

FIG. 6 shows a process of sealing glass;

FIG. 7 shows a process of manufacturing the semiconductor light-emitting device;

FIG. 8 shows a semiconductor light-emitting device in accordance with a conventional technique;

FIG. 9 shows an optical element package in accordance with an embodiment of the present invention;

FIG. 10 shows an optical element package in accordance with a modification of the present invention;

FIG. 11 shows an optical element package in accordance with another modification of the present invention;

FIG. 12 shows an optical element package in accordance with a yet another modification of the present invention; and

FIG. 13 shows an optical element package in accordance with a yet another modification of the present invention.

REFERENCE SIGNS LIST

-   -   1 optical element package     -   2 semiconductor light-emitting device     -   3 mount substrate     -   10 base     -   11, 12 through-hole     -   13 mount portion     -   14 recessed portion     -   15 outer circumferential portion     -   16 protruding portion     -   16 a top surface of protruding portion     -   21, 22 lead     -   21 a, 22 a lead end portion     -   21 b, 22 b pass-through portion     -   21 c, 22 c extending portion     -   21 d, 22 d endmost portion     -   31, 32 insulating material     -   50 LED chip     -   51, 52 wire     -   62 solder joint part     -   73 glass column

DESCRIPTION OF EMBODIMENTS 1. Structure of Optical Element Package

FIGS. 1A and 1B each show an optical element package 1 in accordance with an embodiment of the present invention. FIG. 1A is a top view thereof, and FIG. 1B is a bottom view thereof. FIG. 2 is a cross-sectional view taken along the line X-X of FIG. 1.

A description is given of the structure of the optical element package 1 with reference to FIGS. 1 and 2. For convenience, the lateral direction of the FIG. 1 is defined as the horizontal direction, and the direction orthogonal to the lateral direction is defined as the vertical direction.

The optical element package 1 is used for packaging therein an optical element. The optical element package 1 includes a base 10 having a pair of through-holes 11 and 12, a pair of leads 21 and 22 respectively passing though the through-holes 11 and 12, and insulating materials 31 and 32 respectively filled in the through-holes 11 and 12 to fix the leads 21 and 22 in a state of being insulated from the base 10.

(Structure of Base)

As shown in FIGS. 1A and 1B, the base 10 is substantially in a square shape in the planar view seen in the vertical direction. The central portion of the upper surface of the base is a mount portion 13 on which an optical element is to be mounted.

The through-holes 11 and 12 are opposite to each other with the mount portion 13 therebetween, and provided to penetrate the base 10 in the vertical direction from the upper surface to the bottom surface thereof.

Also, the base 10 has a recessed portion 14 on the upper surface thereof. The mount portion 13 is formed on the bottom of the recessed portion. The base 10 includes an outer circumferential portion 15 that is higher than the mount portion 13.

As shown in FIG. 2, the recessed portion 14 is in the shape of a basin. As shown in FIG. 1A, seen from above, the recessed portion 14 is in a circular shape.

It is desirable that the entirety of such a base 10 is integrally formed of a metal material such as copper.

The inner surface of the recessed portion 14 is covered with a coating layer (unillustrated). The coating layer is formed by layers made of a material selected from among gold, silver, a gold alloy, or a silver alloy, and reflects light emitted from the optical element mounted on the mount portion 13.

The base 10 has a protruding portion 16 on the bottom surface thereof immediately below the mount portion 13.

The height of the protruding portion 16 is set such that the top surface 16 a, which is the bottom level, of the protruding portion 16, is flush with the bottom level of each of the leads 21 c and 22 c.

(Structure of Lead)

The leads 21 and 22 are obtained by bending a long metal plate. The metal plate is made of an iron-nickel alloy, for example.

The leads 21 and 22 have pass-through portions 21 b and 22 b passing through the through-holes 11 and 12, respectively. The pass-through portions 21 b and 22 b are fixed by insulating materials 31 and 32 filled in the through-holes 11 and 12, respectively.

Each of the pass-through portions 21 b and 22 b passing through the through-holes 11 and 12 is offset from the center of each of the through-holes 11 and 12 toward the outer circumference of the base 10. According to FIG. 2, the center of the through-hole 12 is represented by the dashed line A, and the position of the pass-through portion 22 b is represented by the dashed line B. FIG. 2 shows a state where the pass-through portion 22 b is offset toward the outer circumference of the base 10 (on the right side in FIG. 2).

The end portions 21 a and 22 a of the leads 21 and 22 in the vicinity of the mount portion 13 and extending from the pass-through portions 21 b and 22 b are bent toward the inside of the base 10. That is to say, the pass-through portions 21 b and 22 b extend in the vertical direction, and the lead end portions 21 a and 22 a extend in the horizontal direction so that a pad area is formed.

As described above, the position of each of the pass-through portions 21 b and 22 b is offset toward the outer circumference. Accordingly, when each of the lead end portions 21 a and 22 a is set to be longer correspondingly in the horizontal direction, the top of each of the lead end portions 21 a and 22 a is not in contact with the base 10. This can assure the insulation between the leads 21, 22 and the base 10. Thus, since each of the lead end portions 21 a and 22 a is long in the horizontal direction, the pad area is increased. This makes the process of wire bonding easier.

Also, since the position of each of the pass-through portions 21 b and 22 b is offset toward the outer circumference, the distance between the protruding portion 16 and each of the leads 21 and 22 can be longer correspondingly. This is effective in preventing the protruding portion 16, the leads 21 and 22 from shorting out when the package is assembled on the mount substrate 3.

On the other hand, the extending portions 21 c and 22 c of the leads 21 and 22 extending outwardly from the through-holes 11 and 12 are each bent, relative to the pass-through portions 21 b and 22 b, in the direction toward the outer circumference of the base 10, and then the leads extends along the bottom surface of the base 10.

The extending portions 21 c and 22 c each extend beyond the outer circumference of the base 10, and the endmost portions 21 d and 22 d of the leads are each bent in the vertical direction toward the upper surface of the base 10.

The width (W2 in FIG. 1) of each of the endmost portions 21 d and 22 d of the leads is set smaller than the width (W1 in FIG. 1) of each of the extending portions 21 c and 22 c along the bottom surface of the base 10 (see FIG. 5).

The detailed description will be given in the description of the manufacturing method. With this structure, when the leads 21 and 22 are each formed by bending a metal plate, the endmost portions 21 d and 22 d can be easily bent.

Note that, the leads 21 and 22 respectively have opening portions 21 e and 22 e in areas where the leads 21 and 22 are in contact with the insulating materials 31 and 32.

(Structure of Insulating Material)

The insulating materials 31 and 32 are filled in the through-holes 11 and 12 to cover the pass-through portions 21 b and 22 b of the leads 21 and 22.

Furthermore, as shown in FIG. 2, the insulating materials 31 and 32 are filled in the opening portions 21 e and 22 e, and are in contact with the end portions 21 a and 22 a of the leads 21 and 22.

Such insulating materials 31 and 32 secure the leads 21 and 22 in a state of being insulated from the base 10, and seal the through-holes 11 and 12.

Parts of the insulating materials 31 and 32 also intervene between the extending portions 21 c and 22 c of the leads 21 and 22 and the bottom surface of the base 10. This assures the insulation therebetween as well.

As the insulating materials 31 and 32, a material that can fix the leads 21 and 22 within the through-holes 11 and 12 of the base 10 is used. More specifically, although a resin is applicable as the insulating material, soda-lime glass or borosilicate glass is preferable.

Generally, since a glass material is highly viscous compared with a resin when melted, the glass material is effective in joining members even if there is a wide clearance therebetween. Accordingly, if a glass material is used as the insulating materials 31 and 32, the glass material is retained in the through-holes 11 and 12 even when melted so as to be able to stably join the leads 21 and 22.

Also, to enhance the reflectivity of the inner surface of the recessed portion 14, it is also desirable to use highly reflective white glass as the insulating materials 31 and 32.

(Structure of Semiconductor Light-emitting Device 2 and Lighting Fixture)

FIGS. 3A and 3B respectively show a semiconductor light-emitting device 2 where an optical element is provided in the optical element package 1, and a state where this device 2 is mounted on the mount substrate 3.

Here, a light-emitting diode (LED) is used as an optical element. However, a laser diode or the like is also applicable.

As shown in FIG. 3A, the semiconductor light-emitting device 2 is structured as follows. An LED chip 50 is mounted on the mount portion 13 of the optical element package 1. A terminal of the LED chip 50 and the lead end portions 21 a and 22 a are connected by wires 51 and 52. According to this semiconductor light-emitting device 2, a transparent resin is filled in the recessed portion 14 to seal the LED chip 50.

As shown in FIG. 3B, the semiconductor light-emitting device 2 is mounted on the mount substrate 3, is soldered to the extending portions 21 c and 22 c of the leads 21 and 22, and thus is used as a lighting fixture. Note that on the surface of the mount substrate 3, a wiring pattern (unillustrated) is formed of a metal such as copper, and an insulation film 60 is provided to avoid unnecessary electrical contact with the semiconductor light-emitting device 2.

2. Manufacturing Method of Optical Element Package 1 and Semiconductor Light-emitting Device 2

FIG. 4 is a process flow chart showing a manufacturing method of the optical element package 1 and the semiconductor light-emitting device 2.

A description is given with reference to FIG. 4.

In P1-P3, the glass column, the base 10, and the leads 21 and 22 used in a glass sealing process are manufactured.

A material made of oxygen-free copper or a copper alloy is pressed by the press working machine. Thus, the base 10 is manufactured (P1).

A plate material made of an iron-nickel alloy is bent and processed. Thus, the leads 21 and 22 are manufactured (P2). As necessary, the leads 21 and 22 are heated to be 650° C. in the air to undergo oxidation.

A description is given of the lead manufacturing process with reference to FIG. 5. FIG. 5 shows a metal plate that is to be the lead 21 and not yet bent. By bending the metal plate along the broken lines Y1, Y2 and Y3 in FIG. 5, the lead 21 is manufactured.

With regard to the bending of the metal plate along the broken line Y3, since the width W2 of the endmost portion 21 d is set to be smaller than the width W1 of the extending portion 21 c, an angular portion (indicated by C in FIG. 4) is formed on an end portion of the extending portion 21 c.

By pressing glass powder into a columnar shape and temporally burning it, the glass column is manufactured (P3).

Glass Sealing Process (P4):

FIG. 6 shows the glass sealing process. A description thereof is given with reference to FIG. 6.

The base 10 is mounted on a carbon jig 71 (FIG. 6A). The leads 21 and 22 are led through the through-holes 11 and 12 of the base 10 and fixed by a carbon jig 72 (FIG. 6B). The glass column 73 is inserted in each of the through-holes 11 and 12 (FIG. 6C), and heated to a temperature higher than a melting temperature of the glass (e.g. 1000° C.) and then cooled down. While the glass is heated and cooled down, the positions of the leads 21, 22 and the base 10 are fixed by the carbon jigs 71 and 72 (FIG. 6D).

Here, as described above, an angular portion (see C in FIG. 5) is formed on the end portion of each of the extending portions 21 c and 22 c of the leads 21 and 22. As a result, in the process shown in FIG. 6B, the carbon jig 72 fixes this angular portion, thereby being able to hold the leads 21 and 22. Also, the carbon jig 72 can be slid from the endmost portion in the horizontal direction to a position where the angular portion is fixed. Accordingly, the package can be easily assembled.

The heated glass is melted so that part of the melted glass passes through the opening portions 21 e and 22 e of the glass leads 21 and 22, thereby filling the entirety of each of the through-holes 11 and 12. Also, another part of the melted glass flows between the extending portions 21 c and 22 c of the leads 21 and 22 and the bottom surface of the base 10. When cooled down, the glass becomes solidified to be the insulating materials 31 and 32. With these insulating materials 31 and 32, the leads 21 and 22 are secured to the base 10.

Coating is applied to what is assembled as above (P5 in FIG. 4).

In this process, it is desirable that a primary coating is formed by being coated with nickel, and that a material selected from among gold, silver, and a gold or silver alloy is coated thereon.

With this coating, on the entire exposed surface of each of the base 10, the leads 21 and 22, etc., the primary coating made of nickel and the coating layer made of gold, silver or a gold or silver alloy are formed.

Thus, the optical element package 1 is manufactured.

(Manufacture and Fabrication of Semiconductor Light-emitting Device)

With the use of the optical element package 1, the semiconductor light-emitting device 2 is manufactured through a dice bonding process (P6 in FIG. 4), a wire bonding process (P7 in FIG. 4), and an encapsulating process (P8 in FIG. 4).

A description of these processes is given with reference to FIG. 7A. Note that FIG. 7A shows a case as shown in FIG. 3 where there is a reflector but no lens and that FIG. 7B shows a case where there is no reflector but is a lens as a modification.

In the dice bonding process P6, an Au—Sn alloy paste or an Ag paste is applied on the mount portion 13 of the optical element package 1, and then the LED chip 50 is mounted thereon, and the paste is heated to connect the optical element package 1 to the LED chip 50. The heating temperature is 320° C. when the Au—Sn alloy paste is used and 150° C. when the Ag paste is used.

In the wire bonding process P7, a terminal of the LED chip 50 and the lead end portions 21 a and 22 a are connected by wires (Au wires) 51 and 52. Here, as described above, since the lead end portions 21 a and 22 a each extend in the horizontal direction, the lead end portions 21 a and 22 a can be easily joined to the wires 51 and 52.

In the encapsulating process P8, a transparent resin used for a seal (epoxy resin or silicon resin) is flowed into the recessed portion 14 and cured therein to seal the LED chip 50.

In the modification shown by FIG. 7B, since the outer circumferential portion 15 of the base 10 is not formed higher than the central portion thereof, a reflector is not formed. Instead, a lens capping process of mounting the lens 80 to cover the LED chip 50 is added after the wire bonding process. In the encapsulating process, the transparent resin used for a seal is poured between the lens 80 and the base 10 and cured therebetween, thereby sealing the LED chip 50.

Note that as another modification, until the wire bonding process, the reflector may be formed such that the outer circumferential portion 15 of the base 10 is higher than the central portion as shown in FIG. 7A. In the lens capping process and the encapsulating process, the lens 80 may be mounted as shown in FIG. 7B.

The semiconductor light-emitting device 2 manufactured as above is mounted on the mount substrate 3.

As described above, a wiring pattern (unillustrated) is formed on a surface portion of the mount substrate 3, and an insulation film 60 is provided thereon. A cream solder 61 is applied on the wiring pattern at positions of the leads 21 and 22 provided on the mount substrate 3.

When the semiconductor light-emitting device 2 is mounted on the mount substrate 3 and is heated in a reflow oven, the cream solder 61 is melted to solder the extending portions 21 c and 22 c of the leads 21 and 22 to the mount substrate 3. Then, the melted solder flows on the surfaces of the endmost portions 21 d and 22 d and wets them, thereby forming a round fillet on the solder joint part 62. Thus, the strength of the solder joint part 62 is increased. Also, a state of the soldering can be checked by observing the shape of this fillet.

3. Effect by Optical Element Package 1

As described above, the optical element package 1 pertaining to this embodiment can be manufactured as follows. The leads 21 and 22 are fixed in a state of being insulated from the base 10 by the insulating materials 31 and 32. The base 10 and the leads 21 and 22 are made of a thermally conductive metal material, and the leads 21 and 22 are set in the through-holes of the base 10, and a glass material is filled in the through-holes.

Thus, the base 10, and the leads 21 and 22 can be manufactured with high accuracy with the use of press working.

Heat generated from the LED chip 50 is externally transmitted to the well-conductive base 10. Thus, heat is able to be dissipated favorably.

In particular, the extending portions 21 c and 22 c of the leads 21 and 22 extending outwardly from the pass-through portions 21 b and 22 b are bent in the direction toward the outer circumference of the base 10, and thereby extending along the bottom surface of the base 10. Thus, as shown in FIG. 3, when the extending portions 21 c and 22 c are soldered to the mount substrate 3, the top surface 16 a of the protruding portion 16 immediately below the mount portion 13 is in proximity or in contact with the mount substrate 3. As a result, heat generated by the LED chip 50 is transmitted from the mount portion 13 of the base 10 to the portion immediately underneath thereof, thereby being effectively dissipated to the mount substrate 3.

In particular, since the base 10 made of a copper material (oxygen-free copper or copper alloy) is well conductive, excellent heat dissipation properties can be obtained.

Furthermore, the base 10 has the protruding portion 16 on the back side of the mount portion 13. The bottom level of the protruding portion 16 is flush with the bottom level of each of the extending portions 21 c and 22 c. Accordingly, when the device is mounted on the mount substrate 3, the top surface 16 a of the protruding portion 16 is in contact with the mount substrate 3. Therefore, heat is more favorably dissipated to the mount substrate 3.

Also, the leads 21 and 22 are not directly joined to the base 10, but fixed to the base 10 via the insulating materials 31 and 32. In addition, the extending portions 21 c and 22 c of the leads are bent in the direction toward the outer circumference of the base, and are parallel to each other at an interval along the bottom surface of the base 10. As a result, the leads 21 and 22 can be deformed flexibly to some extent.

Accordingly, even if external force is applied to the leads 21 and 22 caused by the thermal expansion difference between the base 10 and the mount substrate 3, since the leads 21 and 22 are deformed to absorb this force, the stress applied to the solder joint part 62 is small. Thus, in the heat cycle test, the solder joint part 62 hardly cracks.

Since the extending portions 21 c and 22 c of the leads 21 and 22 extend beyond the outer circumference of the base 10, and the endmost portions 21 c and 22 c are bent toward the upper surface of the base 10, a fillet is formed on the solder joint part 62 so that the solder joint is strengthened. This is also effective in suppressing the solder crack.

Since the base 10 and the mount substrate 3 are both made of a metal, the thermal expansion difference therebetween is small. This is also effective in suppressing the occurrence of solder crack.

As described in the manufacturing method, the base 10 and the leads 21 and 22 can be manufactured with accuracy, because the optical element package 1 can be manufactured as follows: the base 10 and the leads 21 and 22 are formed by the press working; the leads 21 and 22 are set within the through-holes 11 and 12; and a glass material is filled in the through-holes.

As described above, the positions of the leads 21 and 22 passing through the through-holes 11 and 12 are each offset from the center of each of the through-holes 11 and 12 toward the outer circumference of the base 10, and the lead end portions 21 a and 22 a are each bent toward the center of the base 10. Accordingly, the lead end portions 21 a and 22 a can be easily joined to the wires 51 and 52.

The recessed portion 14 is formed in the central portion of the upper surface of the base 10, and the outer circumferential portion 15 is formed higher than the mount portion 13. Thus, the inner surface of the recessed portion 14 can function as a reflector. In addition, if the inner surface of the recessed portion 14 is coated with silver or a silver alloy, reflectivity of the reflector to blue light is increased.

When the insulating materials 31 and 32 are made of highly reflective white glass, the reflectivity of the reflector can be increased.

Since the insulating materials 31 and 32 are partially intervened between each of the extending portions 21 c and 22 c of the leads and the bottom surface of the base 10, the insulation therebetween can be assured.

Being highly viscous, the glass material is effective in joining members if there is a wide clearance therebetween. Accordingly, if soda-lime glass or borosilicate glass is used as the insulating materials 31 and 32, the leads 21 and 22 can be stably fixed.

Embodiment and Modification

FIG. 9 shows an optical element package in accordance with an embodiment similar to the optical element package 1. FIGS. 10-13 each show an optical element package in accordance with a modification of the optical element package 1. In each drawing, FIG. A is a plan view, FIG. B is a right-side view, FIG. C is a bottom view, FIG. D is a front view, and FIG. E is a cross-sectional view. Note that the illustrations of the left-side view and the back view are omitted, for the left-side view is symmetrical with the right-side view, and the back view is symmetrical with the front view.

Although the optical element package shown in FIG. 10 is basically identical with that shown in FIG. 9, the recessed portion (reflector) is not formed on the upper surface of the base 10.

According to the optical element package shown in FIGS. 11-13, a plurality of mount portions are provided on the upper surface of the base 10, and a plurality of LED chips can be mounted thereon.

According to the optical element package shown in FIG. 11, four mount portions 13 a-13 d are arranged in a line, and a pair of leads 21 and 22 passes through a pair of through-holes 11 and 12.

According to an optical element package shown in FIG. 12, four mount portions 13 a-13 d are disposed in 2 rows*2 columns, and two pairs of leads 21 and 22, 27 and 28 are led through two pairs of through-holes 11 and 12, 17 and 18, respectively.

According to the optical element package shown in FIG. 13, eight mount portions 13 a-13 h are disposed in four rows*two columns, and a pair of leads 21 and 22 are led through a pair of through-holes 11 and 12. Note that according to this optical element package, a recessed portion (reflector) is not formed on the upper surface of the base 10.

As with the optical element package shown in FIGS. 11-13 in which a plurality of LED chips can be mounted, the LED chips each having the same emission color may be mounted. However, LED chips having different emission colors may be mixed. For example, when LED chips with RGB colors are mixed, the emitted color of the entire LED chips is white.

Note that according to the optical element package 1, the mount portion 13 is integrally formed on the upper surface of the base 10. However, the structure in which a second base, different from the base 10, may be fixed to the base 10 in a state of being insulated from the base 10, and the mount portion may be formed on the upper surface of the second base. Here, the number of the second bases each having a mount portion thereon does not need to be one, and a plurality of second bases may be provided.

More specifically, for example, a plurality of second through-holes are provided in the central portion of the base 10, and each second base is made of a metal material in a shape that enables each second base to pass through second through-hole, and a mount portion is formed on the upper surface of each second base. Then, each second base is fixed within the second through-hole via an insulating material such as a glass material.

With this structure, a plurality of optical elements mounted thereon can be operated without mutually shorting out.

Although the through-holes 11 and 12 for leads are provided in plural in the base 10, if the base itself also functions as a terminal, the number of the leads may be one. Accordingly, the number of the through-holes provided in the base may be also one.

INDUSTRIAL APPLICABILITY

The present invention is applicable to an optical element package for packaging therein an optical element such as a light-emitting diode (LED). The present invention relates to an optical semiconductor element and may be used as a lighting fixture.

Since the present invention especially has favorable heat dissipation properties, the present invention is suitable for a high-power optical semiconductor element. 

1. An optical element package for packaging an optical element therein, comprising: a base made of oxygen-free copper or a copper alloy, and having a mount portion on an upper surface thereof for mounting the optical element thereon and a through-hole; a lead passing through the through-hole and to be connected to the optical element; and an insulating material filled in the through-hole and fixing the lead such that the lead is insulated from the base, wherein the lead extends outwardly from the through-hole at one end, and a portion of the lead passing out of the through-hole at the one end is bent in a direction toward an outer circumference of the base so as to extend along the bottom surface of the base.
 2. (canceled)
 3. (canceled)
 4. The optical element package of claim 1, wherein the bottom surface of the base has a protruding portion, and a bottom level of the protruding portion is flush with a bottom level of an extending portion of the lead that extends along the bottom surface of the base.
 5. The optical element package of claim 1, wherein a portion of the lead that passes through the through-hole has been offset from a center of the through-hole in the direction toward the outer circumference of the base, and the lead is bent toward the center of the base at another end in a vicinity of the mount portion.
 6. The optical element package of claim 1, wherein a central portion of the upper surface of the base is recessed so that an outer circumferential portion of the base is higher than the mount portion.
 7. The optical element package of claim 6, wherein a surface of the central portion of the base that is recessed is coated with silver or a silver alloy.
 8. The optical element package of claim 1, wherein the insulating material is made of highly reflective white glass.
 9. The optical element package of claim 1, wherein the one end of the lead extends beyond the outer circumference of the base, and is bent upwardly at an endmost portion thereof.
 10. The optical element package of claim 9, wherein a width of the endmost portion of the lead is smaller than a width of an extending portion of the lead that extends along the bottom surface of the base.
 11. The optical element package of claim 1, wherein the insulating material intervenes between the bottom surface of the base and an extending portion of the lead that extends along the bottom surface of the base.
 12. The optical element package of claim 1, wherein the insulating material is made of soda-lime glass or borosilicate glass.
 13. The optical element package of claim 1, wherein the lead is made of an iron-nickel alloy.
 14. The optical element package of claim 1, further comprising; an auxiliary base portion fixed in a state of being insulated from the base, wherein an upper surface of the auxiliary base portion has a mount portion for mounting the optical element thereon.
 15. The optical element package of claim 14, wherein a plurality of auxiliary base portions are provided for a main body of the base, and an upper surface of each auxiliary base portion has the mount portion.
 16. A semiconductor light-emitting device, wherein an optical element is provided in an optical element package as defined in claim 1, and is connected to the lead by wire bonding.
 17. A lighting fixture, wherein a semiconductor light-emitting device as defined in claim 16 is mounted on a substrate having a wire connected to a driving circuit. 